A calendar has been prepared for a special election to fill the vacancy, with a primary in March and the election in April, Galvin said. Members of the state House will discuss the issue Wednesday, he said.

Smith, a Democrat from Everett, had previously said he would resign and not seek elected office for five years after agreeing to plead guilty in the absentee ballots case.

Federal prosecutors said Smith, a member of the House since 2007, cast ballots for voters who were ineligible or were unaware of ballots being cast in their names.

Investigators said last month that in some cases Smith would intercept ballots before their delivery and cast them himself. They said Smith, a member of the Election Laws Committee, had help intercepting the ballots from "one or more government officials."

Galvin, a Democrat, says he is asking federal prosecutors for more information about Smith's case before deciding if any other steps need to be taken but is reluctant to recommend tightening access to absentee ballots. He says he's interested in finding out which government officials might have helped Smith.

"I would have to remove them," he said emphatically.

Smith's plea agreement called for him to resign Tuesday. Prosecutors said he would plead guilty to two civil rights misdemeanor counts.

Galvin said Tuesday he doesn't know of any plea from Smith in court.

Smith's representatives have generally declined to comment on the case.

Smith wasn't the only elected official accused last year of tampering with absentee ballots.

In October, former East Longmeadow selectman Enrico "Jack" Villamaino pleaded not guilty to 12 voter fraud-related counts after prosecutors accused him of trying to rig absentee ballots during an unsuccessful Republican primary campaign for the Legislature. Investigators said he took absentee ballot applications from the clerk's office and cast some of them after altering the voter registrations of some Democrats to independent.

By law, Massachusetts voters can use absentee ballots, which they can receive in the mail or download on the Internet and then mail back to elections officials, if they plan to be away from their cities or towns on Election Day, have physical disabilities that prevent their voting at polling locations or cannot vote at the polls due to religious beliefs.

Despite the two recent fraud cases, Galvin said he'd be reluctant to clamp down too tightly on access to absentee ballots because that could create an added burden for voters including those serving in the military.

The upcoming special election also would be to fill the seat of state Rep. Joyce Spiliotis, a Democrat from Peabody, who died in November at age 65. Spiliotis, who had won re-election in an uncontested race, was in her fifth term on Beacon Hill.